The pecan tree is the tallest of the hickory group and a member of the walnut family. The pecan tree grows in the wild across much of the Midwest and well into the Deep South, existing in the fertile soil of the river bottom lands across the region. Pecan trees have distinct characteristics that help you identify them.
Look at the size of the pecan tree. According to the Floridata website, the tree has the ability to exceed 180 feet when developing in perfect growing conditions in a natural setting. Most are shorter but still may be around 100 feet tall, with a trunk as wide as 3 feet. The crown of a pecan is large and round, with the branches spreading widely from the trunk.
Check the leaves of pecan trees. They are compound in nature, consisting of as many as 17 or as few as 11 separate smaller leaflets on a long stem. Pick some up from beneath the pecan tree and measure the leaflets. They are 4 to 7 inches long. Measure the rachis, or stem to which the leaflets attach, and you should find it to be between 12 and 20 inches in length.
Smell the leaves after crushing a few of them. They have a somewhat unpleasant odor. They are greenish-yellow on their upper surface, a shade which is paler on the undersides. The "National Audubon Field Guide to Trees" states that pecan leaves will change to yellow in the fall.
Feel the bark with your hands. It has many deep furrows and prominent ridges that are traits of this species. The bark is grayish in younger pecans and a reddish-brown colored bark on the more mature specimens of pecan.
Examine the tree's nuts. The shells are thin and green while still on the tree during the summer and a dark brown as they gradually ripen in the fall. They are oblong, with one end rounded and the other pointed. When ripened, the husks split into four sections, revealing the oily and edible nut.